Up to now, it has been practiced to interconnect a reproducing device for a compact disc (CD), as a recording medium holding digital audio data recorded thereon, and a recording device for a mini-disc (MD), as a recording medium which permits data recording a number of times, and to duplicate the digital audio data, recorded on the compact disc, on the mini-disc, for personal exploitation.
Recently, with the coming into widespread use of personal computers, music distribution services over the Internet also have come to be used, such that, as the user staying at home is able to have the targeted digital audio data distributed over the Internet through use of the personal computers.
The digital audio data, distributed over the Internet, is stored in for example the hard disc of the personal computer so as to be reproduced using the personal computer. The digital audio data may also be duplicated (ripped or dubbed) lo an external memory employing a semiconductor device, termed a memory card, or an external storage medium, such as mini-disc, so as to be reproduced and exploited using a memory card player or a MD player.
It should be noted that a large quantity of the audio data may be stored in the hard disc of the personal computer, or the digital audio data can be duplicated (copied) on an external storage medium, such as a memory card, extremely readily. It may thus be feared that unauthorized duplication of the digital audio data, taken into a personal computer from a compact disc, or audio data distributed over e.g., the Internet and taken into the personal computer, is made repeatedly, thus illicitly impairing the benefit of the copyright owner of the digital audio data.
Thus, in order to develop a unified system of the copyright protecting technique that may be used in common on the global basis, more than 130 business establishments and organizations from the business circles of the phonogram, computers and electronics for domestic use have organized a forum called SDMI (Secure Digital Music Initiative) with a view to preparing a framework preventing illicit use of music files (digital audio data) and to for promoting lawful music distribution services. system of limiting or supervising the number of duplications of the audio data. FIG. 1 shows an instance of employing this system. Referring to FIG. 1, a personal computer 200 is supplied with digital audio data from a CD player 100 or over the Internet 300 to take the digital audio data into its built-in hard disc.
In duplicating the digital audio data, thus taken into the personal computer 200, on so-called memory cards, the number of duplication of the digital audio data is limited on the personal computer 200 to three or less. FIG. 1 shows a case where the same digital audio data is duplicated from the personal computer 200 to each of three memory cards 301 to 303.
The memory cards 301 to 303 each are a new external storage medium which recently is finding use in increasing numbers. Each of the memory cards has a medium identification ID (medium identification information) proper to each memory card. The personal computer 200 is supplied from the memory card, to which the digital audio data is output, with the medium identification ID of the memory card, based on which the management may be performed as to which digital data has been output to which memory card.
If, in the memory card, supplied with the digital audio data from the personal computer 200 and which has stored the digital audio data, the digital audio data has been deleted, as by returning it to the personal computer 200, the number of the memory cards on which the digital audio data has been duplicated is decreased by one, so that duplication of the digital audio data to a new memory card is allowed.
In such system, prepared by SDMI, which imposes limitations on the allowed number of duplicates of digital audio data, up lo three duplicates of the digital audio data, taken into the personal computer 200, are allowed. If the digital audio data, as a duplicate, is deleted as by being returned to the personal computer 200, the number of the duplicates is decreased, so that duplication to eke out the decrease is allowed.
Even although the number of duplications is limited, duplication for personal use is allowed, as conventionally, so that convenience for the user of the digital audio data is not impaired, at the same time as unauthorized duplication of the digital audio data in large quantities is inhibited to prohibit the benefit of the copyright owner of the digital audio data from being illicitly infringed.
Meanwhile, in this system of limiting the number of duplicates of the digital audio data, the outputting of digital audio data from the personal computer 200 to the memory card is termed the check-out, while the deletion of the digital audio data from the memory card which has gone through the check-out of the digital audio data to the personal computer 200 as the source of the digital audio data in a manner of returning the data to the personal computer is termed the check-in.
This system of limiting the number of duplicates of the digital audio data is among the copyright protecting techniques applicable to the case of using the so-called memory card, having the medium identification ID as a recording medium, while it is not applicable to the case of using the mini-disc which is now in widespread use. That is, no medium identification ID proper to each mini-disc is not provided to the mini-disc.
The mini-disc is in widespread use as a recording medium, such that the digital audio data from e.g., the CD player may be recorded on the mini-disc, using a mini-disc recorder. Thus, as for the audio data recorded on the mini-disc, it is necessary that clear distinction can be made between the mini-disc on which recording has been made through a conventional channel not subjected to the duplicate number management and the mini-disc on which recording has been made through a new channel of the check-out/check-in system subjected to the duplicate number management.
If the copyright protection technique of the SDMI system, which manages the allowed number of the duplicates of the digital audio data described above, cannot be applied to the case of using the recording medium which is now finding widespread use, such as mini-discs, it is not possible to prevent unauthorized duplication of the digital audio data to prevent the benefit on the part of the copyright owner of the digital audio data from being infringed illicitly. It is therefore a desideratum that copyright protection technique of the SDMI system, which manages the allowed number of the duplicates of the digital audio data described above can be applied to the mini-discs which are currently in widespread use.
On the other hand, the digital audio data stored on the hard disc or on the memory card are encrypted in a preset manner, while being audio-compressed by a technique exemplified by the ATRAC3 (Acoustic Transform Acoustic Coding).
Moreover, the conventional mini-disc recording and/or reproducing apparatus, while coping with the audio compression technique, fails to cope with the encryption.
Thus, it is not possible with the mini-disc recording and/or reproducing apparatus to discriminate whether the compressed digital audio signals, recorded on the mini-disc, are derived from the Internet or a hard disc or directly from the output of the CD player, and hence the source channel has to be supervised in the perspective of the copyright management.
Unless it is discriminated in the mini-disc recording and/or reproducing apparatus whether the compressed digital audio signals recorded on the mini-disc are compressed and encrypted digital audio signals which should be managed as to the number of allowed duplicates or the compressed and non-encrypted digital audio signals which do not have to be managed as to the number of allowed duplicates, disorder may be produced such as erroneously applying check-in/check-out to the compressed non-encrypted digital audio signals directly duplicated from the CD player.